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  <script>
    var findMaxK = function (nums) {
      let set = new Set(), max = -1
      for (let num of nums) {
        if (set.has(num)) {
          max = Math.max(max, Math.abs(num))
        } else {
          set.add(-num)
        }
      }
      return max
    };
    console.log(findMaxK([-1, 2, -3, 3]))
  </script>
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